10 marker on beri beri disease for md pathology rguhs university exams

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Beriberi Disease - 10 Marker (MD Pathology, RGUHS)

Definition and Etymology

Beriberi (from Sinhalese meaning "extreme weakness") is a systemic disease caused by deficiency of thiamine (Vitamin B1). It primarily affects the peripheral nervous system and the cardiovascular system, and may involve the central nervous system (Wernicke-Korsakoff syndrome).

Robbins, Cotran & Kumar Pathologic Basis of Disease
Bradley and Daroff's Neurology in Clinical Practice

Thiamine - Biochemistry and Role

Thiamine pyrophosphate (TPP) is the active coenzyme form. It is required for:

Oxidative decarboxylation of alpha-keto acids (pyruvate -> acetyl CoA; alpha-ketoglutarate -> succinyl CoA) - key steps in the TCA cycle
Transketolase reactions in the pentose phosphate pathway
Synthesis of neurotransmitters from branched-chain amino acids

Thiamine stores are depleted within 2-3 weeks (faster in high-demand states: pregnancy, lactation, infection, fever). Daily requirement is ~1 mg/day.

Etiology / Causes

Cause	Mechanism
Polished white rice diet	Milling removes thiamine-rich bran; water-soluble thiamine leaches out during washing/cooking
Chronic alcoholism	Decreased intake + impaired intestinal absorption + increased demand
Persistent vomiting	Hyperemesis gravidarum, bulimia nervosa
Gastric disorders	Carcinoma, chronic gastritis, gastric bypass surgery
Prolonged parenteral nutrition without supplementation	No thiamine supplied
Raw fish diet	Contains thiaminase enzyme
Inherited transport defects	Rare; affects thiamine absorption/transport

Classification and Clinical Forms

Beriberi occurs in three main forms:

1. Dry Beriberi (Neuritic/Peripheral form)

Symmetric distal sensorimotor axonal polyneuropathy
Affects both motor and sensory (and autonomic) systems
Numbness, paresthesias, burning pain in the feet (distal predominance due to length-dependent process)
Weakness first appears in finger/wrist extensors and ankle dorsiflexors
Loss of ankle deep tendon reflexes
In severe cases: flaccid paralysis mimicking Guillain-Barre syndrome
No cardiac failure

2. Wet Beriberi (Cardiac/Edematous form)

Peripheral neuropathy PLUS cardiovascular involvement
High-output cardiac failure (due to peripheral vasodilation from thiamine deficiency)
Features: cardiomegaly, dilated cardiomyopathy, tachycardia, dyspnea, peripheral edema (biventricular)
Elevated jugular venous pressure, bounding pulse
May be associated with pulmonary hypertension (reversible with thiamine)
Burning tongue and peripheral edema are characteristic

3. Infantile Beriberi

Occurs in breastfed infants (2-4 months) of thiamine-deficient mothers eating polished rice
Does NOT resemble adult beriberi
Prodrome: Anorexia, vomiting, poor weight gain, restlessness
Acute cardiac symptoms: dyspnea, cyanosis, acute heart failure - can be rapidly fatal
Laryngeal nerve palsy: hoarseness, dysphonia, progressing to aphonia (classic sign)
CNS manifestations: drowsiness, ophthalmoplegia, convulsions
Treatable with parenteral thiamine 5-20 mg (lifesaving if given promptly)

4. Wernicke Encephalopathy / Wernicke-Korsakoff Syndrome (CNS Beriberi)

This is the central nervous system manifestation - particularly emphasized in pathology exams:

Clinical triad of Wernicke encephalopathy:

Acute confusion/delirium
Ophthalmoplegia (paralysis of eye muscles)
Ataxia (cerebellar)
(Full triad present in only ~1/3 of cases)

If untreated, progresses to Korsakoff syndrome (largely irreversible):

Profound short-term memory loss
Confabulation
Anterograde and retrograde amnesia

Pathology (Morphology) - HIGH YIELD for MD Pathology

Peripheral Nerve (Dry/Wet Beriberi)

Axonal degeneration (not primarily demyelination)
Reduced amplitude of sensory and motor nerve action potentials on electrodiagnostic studies
Normal or mildly reduced conduction velocity
Neuropathic changes on EMG

Heart (Wet Beriberi)

Biventricular dilatation and hypertrophy (dilated cardiomyopathy)
High-output failure due to peripheral vasodilation (AV shunting)
Myocardial interstitial edema
Fatty change in myocardial fibers (in severe/chronic cases)

Brain (Wernicke Encephalopathy) - Gross and Micro

Sites affected (preferential, due to high thiamine demand):

Mammillary bodies (most characteristic)
Walls of the 3rd and 4th ventricles
Periaqueductal grey matter
Anterior and centromedian thalamus (dorsomedial nucleus - correlates best with memory disturbance in Korsakoff syndrome)
Superior and inferior colliculi
Hypothalamus (occasionally)

Histopathology:

Acute: Dilated capillaries with prominent endothelial cells; capillary leakage producing petechial/microscopic hemorrhages; neuronal swelling
Subacute/Chronic: Necrosis with macrophage infiltration; hemosiderin-laden macrophages in cystic spaces; gliosis (reactive astrocytosis)
Alpha-ketoglutarate dehydrogenase deficiency in astrocytes leads to microglial activation and glutamatergic excitotoxicity

(Robbins & Kumar Basic Pathology; Robbins, Cotran & Kumar Pathologic Basis of Disease)

Investigations / Diagnosis

Investigation	Findings
Erythrocyte transketolase activity (ETKA)	Reduced; gold standard test
ETKA + TPP stimulation test	>25% increase confirms thiamine deficiency
Serum/blood thiamine level	Reduced
ECG	Sinus tachycardia, non-specific changes
Echocardiography	Dilated cardiomyopathy, high cardiac output
Nerve conduction studies	Reduced amplitude (axonal), normal/mildly slowed velocity
CSF	Usually normal (mildly elevated pressure if CHF present)

Treatment

Acute stage: IV thiamine 100 mg immediately (before giving IV glucose - glucose infusion without thiamine can precipitate/worsen Wernicke encephalopathy)
Infantile beriberi: Parenteral thiamine 5-20 mg (lifesaving)
Long-term: Balanced diet with thiamine-rich foods + oral thiamine/multivitamin supplementation
Wernicke encephalopathy reverses with thiamine; Korsakoff syndrome is largely irreversible

Prevention

Substitution of polished rice with parboiled or undermilled rice (retains thiamine)
Fortification of rice/bread with thiamine
Dietary diversification (whole grains, legumes, meat, nuts, legumes)
Supplementation in high-risk groups (lactating mothers, alcoholics, patients on parenteral nutrition)
Avoidance of thiaminase-containing raw fish

(Park's Textbook of Preventive and Social Medicine)

Summary Box (RGUHS Exam Recall)

Feature	Dry Beriberi	Wet Beriberi	Infantile Beriberi
Predominant lesion	Peripheral neuropathy	Cardiac failure + neuropathy	Cardiac + CNS
Edema	Absent	Present	May be present
Heart failure	Absent	Present (high-output)	Acute, rapidly fatal
Key sign	Foot drop, glove-stocking sensory loss	Tachycardia, bounding pulse	Aphonia

Key Pathology Points for RGUHS:

Beriberi = axonal neuropathy (not demyelinating)
Wet beriberi = high-output cardiac failure (peripheral vasodilation)
Wernicke: mammillary bodies + 3rd/4th ventricle walls - hemorrhage and necrosis - hemosiderin-laden macrophages
Korsakoff = dorsomedial thalamic nucleus lesion - memory disturbance
Do NOT give IV dextrose before thiamine in suspected Wernicke encephalopathy

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